Rounding Decimals - PowerPoint

In the realm of Year 4 mathematics, specifically under the topic of fractions and decimals, students are introduced to the concept of rounding decimals to the nearest whole number. The process involves understanding that a decimal number lies between two whole numbers and deciding which of those it is closest to. For instance, decimals ranging from 1.1 to 1.4 are nearer to 1 and thus are rounded down, while decimals from 1.6 to 1.9 are closer to 2 and are rounded up. The number 1.5, being equidistant from both 1 and 2, is always rounded up according to mathematical convention.

The rounding rules are further clarified with simple mnemonics: numbers with a decimal part from 5 to 9 are rounded up, while those with a decimal part from 0 to 4 are rounded down. To assist in visualising and applying these rules, number lines are employed as a teaching tool. Students are encouraged to use number lines to round a series of decimal numbers, such as 3.8, 6.3, and 5.6, to their nearest whole numbers, with 3.8 rounding up to 4, 6.3 rounding down to 6, and 5.6 rounding up to 6. These exercises help solidify their understanding of rounding decimals and prepare them for more advanced numerical operations.